Roland TR-808M User manual

Model 8-448 ver. 3.2
INSTALLATION MANUAL
© 2010 CHD Elektroserv is

TR808
TR808TR808
TR808-
--
-M
M M
M
MIDI Interface For Roland TR
MIDI Interface For Roland TRMIDI Interface For Roland TR
MIDI Interface For Roland TR-
--
-808
808808
808
Model 8
Model 8 Model 8
Model 8-
--
-448 ver. 3.2
448 ver. 3.2448 ver. 3.2
448 ver. 3.2
2
Copyright © 2010 CHD Elektroservis. All rights reserved.
No part of this publication may be reproduced in any form without the written permission of CHD Elektroservis.
Contents
page
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. MIDI interface kit components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. General instruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. MIDI interface installation procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. TR-808 cover panel disassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2. Electric and mechanic ground adjustment . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.3. "SYNC" connector and switch replacement . . . . . . . . . . . . . . . . . . . . . . . . 5
2.4. Connecting the interface cable to the TR-808 main board . . . . . . . . . . . . . . . . 7
2.5. LED indicator montage into the "START / STOP" button . . . . . . . . . . . . . . . . . 10
2.6. MIDI interface main board installation . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.7. TR-808 assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3. New functions of TR-808 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.1. "SYNC" switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.2. "SYNC" connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.3. "START /STOP" button . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.4. Connection to MIDI system. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4. DAC Calibration procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Manufacturer :
CHD Elektroservis
9.května 78/35, 198 00 Praha 9, Czech Republic
www.chd-el.cz
[e-mail]

TR808
TR808TR808
TR808-
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-M
M M
M
MIDI Interface For Roland TR
MIDI Interface For Roland TRMIDI Interface For Roland TR
MIDI Interface For Roland TR-
--
-808
808808
808
Model 8
Model 8 Model 8
Model 8-
--
-448 ver. 3.2
448 ver. 3.2448 ver. 3.2
448 ver. 3.2
3
Copyright © 2010 CHD Elektroservis. All rights reserved.
No part of this publication may be reproduced in any form without the written permission of CHD Elektroservis.
1. INTRODUCTION
The TR-808 MIDI retrofit enables your Roland TR-808 to be synchronized with other MIDI
devices and work like polyphonic velocity sensitive MIDI drum expander. More over all original features
of the TR-808 are not changed. The instrument can be used exactly the same way as before the
interface installation.
1.1. MIDI INTERFACE KIT COMPONENTS
The TR-808 MIDI interface kit package contains all necessary components and material for the
installation, including manual with detailed description of the installation procedure. The TR-808 kit
package contains:
[1] MIDI Interface main board (MAIN) including the self-adhesive supports
[2] Synchronization terminals board (SYNC IN/OUT) including the material and cables (screws,
washers and plastic stripes)
[3] 20-core multi-cable with the connector and indication LED
[4] Ground cable with the isolating capacitor
[5] Special MIDI cable - reduction
[6] CD-ROM with user and installation manuals and support software
1.2. GENERAL INSTRUCTION
Installation of all interface components is simple. There will be no major problems during the
installation procedure if you follow instructions from this manual exactly.
It is not necessary to drill any holes in the vintage instrument - all changes can be replaced
without visible changes. The interface can be removed and the instrument can be restored back to the
original appearance at any time if necessary.

TR808
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MIDI Interface For Roland TR
MIDI Interface For Roland TRMIDI Interface For Roland TR
MIDI Interface For Roland TR-
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-808
808808
808
Model 8
Model 8 Model 8
Model 8-
--
-448 ver. 3.2
448 ver. 3.2448 ver. 3.2
448 ver. 3.2
4
Copyright © 2010 CHD Elektroservis. All rights reserved.
No part of this publication may be reproduced in any form without the written permission of CHD Elektroservis.
Before starting the work prepare yourself an small and medium size Phillips screwdrivers, pincers
or scissors, pliers, soldering iron (with soft iron and soldering paste), electric or manual drill with the 5
mm caliber driller, knife and an universal glue.
Attention ! It is necessary to disconnect the instrument form main prior the installation, or
else there is high risk of the electric shock injury !
Manufacturer is not responsible for any eventual mechanical or electrical damage to the
Roland TR-808 instrument caused by violation of described installation procedure or by
careless manipulation during the installation of the MIDI interface !
2. MIDI INTERFACE INSTALLATION PROCEDURE
2.1. TR-808 COVER PANEL DISASSEMBLY
a) Unscrew three screws on the front panel (pic. 1-3), three screws on the rear panel (pic. 1-1)
and four screws on the top panel of the TR-808 (pic. 1-1). Do not lose the screws. They will be used
again after the MIDI kit installation.
b) Carefully lift up the rear side of the TR-808 cover panel, move the entire panel approx. 2 cm
towards yourself and lift up the front side and turn over the entire cover panel of the TR-808
backwards. We recommend to place it on the soft textile pad, to prevent the panel from the damage.
2.2. ELECTRIC AND MECHANIC GROUND ADJUSTMENT
Mechanic and electric grounds are directly interconnected on the TR-808. This galvanic
interconnection can make problems when connecting the TR-808 in the loudspeaker systems. Strong
hum can occur in such a case. It is necessary to isolate both grounds by replacing the ground cable to
eliminate these problems.
This adjustment is not required for correct MIDI interface functionality.
If you do not need to isolate the electric and mechanic grounds leave this
chapter out.
a) Unsolder the green ground cable, going out of the output
connectors board in the front cover, form the soldering hole screwed to rear
panel (pic. 2-1).

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MIDI Interface For Roland TRMIDI Interface For Roland TR
MIDI Interface For Roland TR-
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808808
808
Model 8
Model 8 Model 8
Model 8-
--
-448 ver. 3.2
448 ver. 3.2448 ver. 3.2
448 ver. 3.2
5
Copyright © 2010 CHD Elektroservis. All rights reserved.
No part of this publication may be reproduced in any form without the written permission of CHD Elektroservis.
b) Unsolder the second end of the cable form the soldering pad on the output connectors board
(pic. 2-2). Be very careful here, the soldering pad is badly accessible. There is a risk of the damage of
the surrounding parts.
c) Unsoldered ground cable replace with the cable supplied with the MIDI kit package (part [4] of
the delivery). Solder any side of the cable back to the soldering pad and the other end to the soldering
lug screwed to rear panel of TR-808. Both sides of ground cable are interchangeable. They can be
swapped. Be very careful when soldering on the outputs board.
2.3. "SYNC" CONNECTOR AND SWITCH REPLACEMENT

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MIDI Interface For Roland TR
MIDI Interface For Roland TRMIDI Interface For Roland TR
MIDI Interface For Roland TR-
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808808
808
Model 8
Model 8 Model 8
Model 8-
--
-448 ver. 3.2
448 ver. 3.2448 ver. 3.2
448 ver. 3.2
6
Copyright © 2010 CHD Elektroservis. All rights reserved.
No part of this publication may be reproduced in any form without the written permission of CHD Elektroservis.
a) Use pincers or scissors to cut the plastic stripes on the cable bunch going from 7-pin and 3-
pin connectors on the board in the front cover of TR-808 to the SYNC connector and switch and to the
output board on the rear panel of the TR-808 front cover (pic. 3-1).
b) Vertically pull the flat 7-pin connector to disconnect it from the TR-808 board (pic. 3-2).
c) Unscrew two screws holding the SYNC switch on the rear panel and remove it. (pic. 3-3).
Attention! Do not lose two supports from between the panel and switch.
d) Unscrew two screws holding the SYNC connector on the rear panel and remove it. (pic. 3-4).
Use the pliers to hold the nuts.
e) Save the original cable bunch with the DIN connector, switch, screws, nuts and washers for
eventual future removal of the kit and restoring the original TR-808. (pic. 3-5).
f) Place the new interface "SYNC IN/OUT" board (part [2] of the delivery, pic. 3-6) to fit the
rectangular slot for the switch in the rear panel. Screw the board to the TR-8080 panel. Use two
screws (part of the "SYNC IN/OUT" board, pic. 3-7). Do not forget to use washers under the screw
heads to prevent the TR-808 panel from damage and scratches.

TR808
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MIDI Interface For Roland TR
MIDI Interface For Roland TRMIDI Interface For Roland TR
MIDI Interface For Roland TR-
--
-808
808808
808
Model 8
Model 8 Model 8
Model 8-
--
-448 ver. 3.2
448 ver. 3.2448 ver. 3.2
448 ver. 3.2
7
Copyright © 2010 CHD Elektroservis. All rights reserved.
No part of this publication may be reproduced in any form without the written permission of CHD Elektroservis.
g) Push the flat 7-pin connector on the cable bunch of the "SYNC IN/OUT" board in unoccupied
plug on the TR-808´s main board (pic. 3-8). The connector has the lock to prevent to plug it the other
way around.
h) Use the plastic strips (part of "SYNC IN/OUT" board delivery) to tie the cable bunches of 7-pin
and 3-pin connectors on the TR-808 board. (pic. 3-9). Remove the ends of the stripes with pincers or
scissors. (pic. 3-10).
2.4. CONNECTING THE INTERFACE CABLE TO THE TR-808 MAIN BOARD
Individual cables of the unpopulated end of the 20-core flat multi-cable (part [3] of the delivery)
must be soldered to the particular pads of the TR-808´s main board. Use the micro soldering iron with
sharper head. It is necessary to work carefully to not damage surrounding points on the board. Since
the TR-808 is an old machine the oxidation of the soldering pads is presumable. Use the soldering
paste is highly recommended for quality soldering.
Shielding cover is mounted on TR-808's main board. It is necessary to remove it before 20-core
flat multi-cable montage. Then all soldering pads are accessible very well. Transistors whose leads are

TR808
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MIDI Interface For Roland TR
MIDI Interface For Roland TRMIDI Interface For Roland TR
MIDI Interface For Roland TR-
--
-808
808808
808
Model 8
Model 8 Model 8
Model 8-
--
-448 ver. 3.2
448 ver. 3.2448 ver. 3.2
448 ver. 3.2
8
Copyright © 2010 CHD Elektroservis. All rights reserved.
No part of this publication may be reproduced in any form without the written permission of CHD Elektroservis.
used are clearly marked on the board by graphical symbols. Transistors have
always three leads, the middle one is always collector (C) with emitor (E) and basis
(B) on its sides (pic. 4-1).
Individual cores of the flat multi-core cable are numbered from 1 to 20. Cable
number 1 has different color (red). Soldering pads for individual cables on the TR-
808’s main board are described on the picture 4-2 and following table. Pictures 4-3 to 4-19 depict
soldering pads in detail, pic. 4-20 is showing the finished connection of the cables to TR-808’s board.
Table – Soldering pads on TR-808’s board
Wire Nr. Signal name Solder pad Pic. Nr. Note
1 Bass Drum Trig collector of Q40 4-3 colored wire
2 Snare Drum Trig collector of Q46 4-4
3 Low Tom / Low Conga Trig collector of Q51 4-5
4 Mid Tom / Mid Conga Trig collector of Q54 4-6
5 High Tom / High Conga Trig collector of Q57 4-7
6 Rim Shot / Claves Trig collector of Q60 4-8
7 Hand Clap / Maracas Trig collector of Q29 4-9
8 Cow Bell Trig collector of Q5 4-10
9 Cymbal Trig collector of Q6 4-11
10 Open Hi-Hat Trig collector of Q7 4-12

TR808
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MIDI Interface For Roland TR
MIDI Interface For Roland TRMIDI Interface For Roland TR
MIDI Interface For Roland TR-
--
-808
808808
808
Model 8
Model 8 Model 8
Model 8-
--
-448 ver. 3.2
448 ver. 3.2448 ver. 3.2
448 ver. 3.2
9
Copyright © 2010 CHD Elektroservis. All rights reserved.
No part of this publication may be reproduced in any form without the written permission of CHD Elektroservis.
Table – Soldering pads on TR-808’s board (continue)
Wire Nr. Signal name Solder pad Pic. Nr. Note
11 Closed Hi-Hat Trig collector of Q8 4-13
12 Trig Lock emitter of Q32 4-14
13 Trig Off kolektor of Q31 4-15
14 LED – anode none - see LED montage
15 LED – cathode none - see LED montage
16 +15V upper lead of
resistor R79 4-16
17 +5V
18 +5V emitter of Q18 4-17 both wires 17 and 18 will be
soldered to this pad
19 GND
20 GND emitter of Q20 4-18 both wires 19 and 20 will be
soldered to this pad

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MIDI Interface For Roland TR
MIDI Interface For Roland TRMIDI Interface For Roland TR
MIDI Interface For Roland TR-
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-808
808808
808
Model 8
Model 8 Model 8
Model 8-
--
-448 ver. 3.2
448 ver. 3.2448 ver. 3.2
448 ver. 3.2
10
Copyright © 2010 CHD Elektroservis. All rights reserved.
No part of this publication may be reproduced in any form without the written permission of CHD Elektroservis.
After all 18 wires are soldered and checked, shielding cover can be mounted back to TR-808’s
board.
2.5. INDICATOR LED MONTAGE INTO THE "START / STOP" BUTTON
a) Turn over the front cover and pull out the "START / STOP" button cap. Use two screwdrivers if
necessary. Put the carton paper or textile under the screwdrivers to prevent the damage of the TR-808
front panel (pic. 5-1).
b) The "START / STOP" button cap consists of three parts. Take off the transparent cover from
the carrier part, holding the carrier part with the pliers as shown on picture 5-2. There is a paper label
with the "START / STOP" legend between these two plastic parts (pic. 5-3).

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MIDI Interface For Roland TR
MIDI Interface For Roland TRMIDI Interface For Roland TR
MIDI Interface For Roland TR-
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-808
808808
808
Model 8
Model 8 Model 8
Model 8-
--
-448 ver. 3.2
448 ver. 3.2448 ver. 3.2
448 ver. 3.2
11
Copyright © 2010 CHD Elektroservis. All rights reserved.
No part of this publication may be reproduced in any form without the written permission of CHD Elektroservis.
c) There are three holes underneath the carrier part. Two cross-shaped and one circular. The
circular hole must be redrilled to 5 mm caliber right through (pic. 5-4). After the drilling is finished clean
the hole with the knife (pic. 5-5).
d) Assemble all three parts together having the hole for LED on the left (pic. 5-6).
e) Pull the LED connected to the flat cable through the "START / STOP" button hole in the front
cover (pic. 5-7) and insert it in the prepared hole in the "START / STOP" button. Fix the LED with the
drop of the glue. (pic. 5-8).
f) Put the button cap with the LED back on the "START / STOP" button, having the LED on the
left side.
2.6. MIDI INTERFACE MAIN BOARD INSTALLATION

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MIDI Interface For Roland TRMIDI Interface For Roland TR
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808808
808
Model 8
Model 8 Model 8
Model 8-
--
-448 ver. 3.2
448 ver. 3.2448 ver. 3.2
448 ver. 3.2
12
Copyright © 2010 CHD Elektroservis. All rights reserved.
No part of this publication may be reproduced in any form without the written permission of CHD Elektroservis.
a) Cleanse (degrease) the lower part of the TR-808 bottom to place there the interface main
board "MAIN" (part [1] of the delivery, pic. 6-1).
b) Remove the protective foil form the self-adhesive supports of the "MAIN" board (pic. 6-2).
c) Apply the interface "MAIN" board to the lower part of the TR-808 bottom (pic. 6-3) than fix the
self-adhesive supports by pressing down (pic. 6-4).
2.7. TR-808 ASSEMBLY
The TR-808 retrofit is now installed. TR-808 assembly is the last step of the installation
procedure.
a) Plug the 10-pin connector going from the "SYNC IN/OUT" board in the interface "MAIN"
board. The orientation of the connector is given by the connector lock (pic. 7-1).
b) Plug the 20-pin connector of the multi-core cable soldered to the TR-808 board in interface
"MAIN" board. The orientation of the connector is given by the connector lock (pic. 7-2).
c) Turn the front cover of the TR-808 over the bottom part and move the edge of the front cover
over the supports on the front side of the bottom part.
d) Move the front cover backwards and place its rear side to fit the plastic sides of the TR-808.

TR808
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MIDI Interface For Roland TR
MIDI Interface For Roland TRMIDI Interface For Roland TR
MIDI Interface For Roland TR-
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-808
808808
808
Model 8
Model 8 Model 8
Model 8-
--
-448 ver. 3.2
448 ver. 3.2448 ver. 3.2
448 ver. 3.2
13
Copyright © 2010 CHD Elektroservis. All rights reserved.
No part of this publication may be reproduced in any form without the written permission of CHD Elektroservis.
e) Screw back the three screws on the front panel TR-808 (pic. 7-3), three screws on the rear
panel (pic. 7-4) and four screws on the top panel (pic. 7-5).
The installation of the MIDI kit is now complete and TR-808 is ready to communicate over the
MIDI. Please read carefully the user manual first.
See “DAC Calibration Procedure” chapter if a malfunction occurs in triggering of TR-808’s
instruments via MIDI.
3. NEW FUNCTIONS OF TR-808
3.1. "SYNC" SWITCH
"SYNC" switch on the rear panel has now 3 positions. In the upper or lower positions, all TR-808
functions remain the same as before installation of the MIDI retrofit (DIN-SYNC OUT, DIN-SYNC IN).
The middle position switches on the MIDI input.

TR808
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MIDI Interface For Roland TR
MIDI Interface For Roland TRMIDI Interface For Roland TR
MIDI Interface For Roland TR-
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-808
808808
808
Model 8
Model 8 Model 8
Model 8-
--
-448 ver. 3.2
448 ver. 3.2448 ver. 3.2
448 ver. 3.2
14
Copyright © 2010 CHD Elektroservis. All rights reserved.
No part of this publication may be reproduced in any form without the written permission of CHD Elektroservis.
3.2. "SYNC" CONNECTOR
The 5-pin "DIN SYNC" connector on the TR-808 rear panel is replaced with 7-pin one. Pins Nr.1
to 5 have the original functionality, new pins Nr. 6 and 7 are used for MIDI input. For the normal DIN-
SYNC operation use standard 5 pin cable, same as before MIDI kit installation. For the MIDI
communication (Sync switch in the middle position) please use special 7-pin MIDI cable/reduction
supplied with in the TR-808 MIDI kit package.
3.3. "START /STOP" BUTTON
The "START / STOP" button on the TR-808 panel has the same function as on original non-
retrofitted instrument. LED under the button indicates the MIDI mode ("SYNC" switch in the middle
position).
3.4. CONNECTION TO MIDI SYSTEM
It is necessary to use special MIDI cable (part of delivery) for connection of TR-808 to MIDI
system. For TR808’s “SYNC” connector use the 7-pin connector side of the cable, for output from the
MIDI sequencer or MIDI master keyboard the standard 5-pin side of the cable.
For proper control of TR-808 via MIDI bus, "SYNC" switch on TR-808’s rear panel must be in
central position and host MIDI system must be able to transmit M IDI Clock, Transport (Start, Stop,
Continue) and Note-On commands.

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MIDI Interface For Roland TRMIDI Interface For Roland TR
MIDI Interface For Roland TR-
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808808
808
Model 8
Model 8 Model 8
Model 8-
--
-448 ver. 3.2
448 ver. 3.2448 ver. 3.2
448 ver. 3.2
15
Copyright © 2010 CHD Elektroservis. All rights reserved.
No part of this publication may be reproduced in any form without the written permission of CHD Elektroservis.
4. DAC CALIBRATION PROCEDURE
Problem with multiple triggering of TR-808’s sound generators can occur at some TR-808
drummachine – more instruments are sounding after just one instrument is launched via MIDI
command. It is given by variability of parameters of transistors used in launching circuits of TR-808’s
sound generators. In that case, it is necessary to calibrate outputs of the interface.
Calibration procedure can be done via special MIDI System Exclusive messages transmitted to
the interface. Form of messages is :
F0 00 20 21 7F 62 30 03 dd xx F7 [hex]
where dd databyte is calibration constant and xx byte is checksum (please refer MIDI SYSTEM
EXCLUSIVE COMMUNICATION manual for details about checksum calculating).
Calibration constant is set to 127 during production. If problem described above occurs,
calibration constant must be decreased. Valid values of calibration constant are from 00h to 7Fh.
SysEx messages for some values shows table below.
Table – SysEx messages for some calibration constants
Calibration
constant
Corresponding MIDI SysEx
message [hex]
Calibration
constant
Corresponding MIDI SysEx
message [hex]
127 F0 00 20 21 7F 62 30 03 7F 6C F7 64 F0 00 20 21 7F 62 30 03 40 2B F7
124 F0 00 20 21 7F 62 30 03 7C 6F F7 60 F0 00 20 21 7F 62 30 03 3C 2F F7
120 F0 00 20 21 7F 62 30 03 78 73 F7 56 F0 00 20 21 7F 62 30 03 38 33 F7
116 F0 00 20 21 7F 62 30 03 74 77 F7 52 F0 00 20 21 7F 62 30 03 34 37 F7
112 F0 00 20 21 7F 62 30 03 70 7B F7 48 F0 00 20 21 7F 62 30 03 30 3B F7
108 F0 00 20 21 7F 62 30 03 6C 7F F7 44 F0 00 20 21 7F 62 30 03 2C 3F F7
104 F0 00 20 21 7F 62 30 03 68 03 F7 40 F0 00 20 21 7F 62 30 03 28 43 F7
100 F0 00 20 21 7F 62 30 03 64 07 F7 36 F0 00 20 21 7F 62 30 03 24 47 F7
96 F0 00 20 21 7F 62 30 03 60 0B F7 32 F0 00 20 21 7F 62 30 03 20 4B F7
92 F0 00 20 21 7F 62 30 03 5C 0F F7 28 F0 00 20 21 7F 62 30 03 1C 4F F7
88 F0 00 20 21 7F 62 30 03 58 13 F7 24 F0 00 20 21 7F 62 30 03 18 53 F7
84 F0 00 20 21 7F 62 30 03 54 17 F7 20 F0 00 20 21 7F 62 30 03 14 57 F7
80 F0 00 20 21 7F 62 30 03 50 1B F7 16 F0 00 20 21 7F 62 30 03 10 5B F7
76 F0 00 20 21 7F 62 30 03 4C 1F F7 12 F0 00 20 21 7F 62 30 03 0C 5F F7
72 F0 00 20 21 7F 62 30 03 48 23 F7 8 F0 00 20 21 7F 62 30 03 08 63 F7
68 F0 00 20 21 7F 62 30 03 44 27 F7 4 F0 00 20 21 7F 62 30 03 04 67 F7
If there are some problems with multiple triggering of TR-808’s sound generators after the
interface installation (when calibration constant is set to 127), set lower calibration constant and then
try functionality of TR-808. If problem persists, decrease calibration constant repeatedly up until all
sound generators are launched correctly.
Calibration constant is stored in internal interface’s memory so new value isn’t lost after TR-808
is turned off and the interface will work with it during all next sessions.

7